When a character's last balloon pops in Hanging, they fall off the bottom of the screen. They're floating over a lava flow.
In Stampede Run, one of the difficulty upgrades that was introduced is having to navigate a large cluster of moving cars and buses. Runners are going along with the cars, and you can knock them down...
Stampede Run can induce this with some of the obstacle arrangements, such as jumping a row of parked police cars and then dodging a bus that's coming right at you. What's that bus heading straight toward?